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Form Factor BATES New technique: polarized beam and target Exploits unique features of BLAST »internal target: low dilution, fast spin reversal »large acceptance: simultaneous measurement of all Q 2 points »symmetric detector: ratio measurement Different systematics »insensitive to P b and P t Q 2 = 0.07 – 0.9 (GeV/c) 2 »overlap with JLab data and RpEX (future exp. at Bates to measure r p )
Citation preview
Precision Measurement of GE
p/GMp with BLAST
Chris CrawfordMIT Laboratory for Nuclear Sciencefor the BLAST collaboration
Motivation
†Nucleon Electromagnetic Form Factors, Haiyan Gao, Int. J. of Mod. Phys. E, 12,
No. 1, 1-40(Review) (2003)
Form Factor Ratio @ BATES
New technique: polarized beam and target Exploits unique features of BLAST
» internal target: low dilution, fast spin reversal» large acceptance: simultaneous measurement of all Q2 points » symmetric detector: ratio measurement
Different systematics » insensitive to Pb and Pt
Q2 = 0.07 – 0.9 (GeV/c) 2 » overlap with JLab data
and RpEX (future exp.at Bates to measure rp)
Asymmetry Super-ratio Method
Polarized cross section
Super-ratio
Detector Package
BLAST CoilsBackward-Angle TOFTOF ScintillatorsWire ChambersCerenkov DetectorsNeutron DetectorsLADS Detectors
BLAST
Wire Chamber Tracking
Garfield drift time simulation Newton-Rhapson track fitter
200μm resolution 20:1 signal to noise ratio
Preliminary Data
Theta Resolution
Beam AsymmetryYield
Projected Results
Statistics» A1, A2
Systematics» θ*
1, θ*2
Δp, Δθ, Δβ
Errors are minimized as a function of β (target spin angle)
BLAST Collaboration
R. Alarcon, E. Geis, J. Prince, B. Tonguc, A. YoungArizona State University
J. Althouse, C. D’Andrea, A. Goodhue, J. Pavel, T. Smith,
Dartmouth CollegeT. Akdogan, W. Bertozzi, T. Botto, M. Chtangeev,
B. Clasie, C. Crawford, A. Degrush, K. Dow, M. Farkhondeh, W. Franklin, S. Gilad,
D. Hasell, E. Ilhoff, J. Kelsey, H. Kolster, A. Maschinot, J. Matthews, N. Meitanis,
R. Milner, R. Redwine, J. Seely, S.Sobczynski, C. Tschalaer, E. Tsentalovich,
W. Turchinetz, Y. Xiao, H. Xiang, C. Zhang, V. Ziskin, T. Zwart
Massachusetts Institute of TechnologyBates Linear Accelerator Center
D. Dutta, H. Gao, W. XuDuke University
J. Calarco, W. Hersman, M. Holtrop, O. Filoti, P. Karpius, A. Sindile, T. Lee
University of New Hampshire
J. RapaportOhio University
K. McIlhany, A. MosserUnited States Naval Academy
J. F. J. van den Brand, H. J. Bulten, H. R. Poolman
Vrije Universitaet and NIKHEF
W. Haeberli, T. WiseUniversity of Wisconsin